- `stdout.isTTY` controls whether list reporter updates lines or just adds them;
- `env.CI` is used in a few places to affect the defaults:
- whether to open interactive html;
- default reporter dot/line;
- default terminal reporter added to non-terminal reporters;
- `env.PWTEST_SKIP_TEST_OUTPUT` is removed;
- `env.PW_TEST_DEBUG_REPORTERS` is introduced specifically for tests.